Highly selective separation and recovery of Pd(II) from the automotive catalyst residue with the thiocarbamoyl substituted azothiacalix[4]arene derivative

ABSTRACT

New ligand, namely, 5, 11, 17, 23-tetrakis-((p-chlorophenyl) azo)-25,26,27,28-tetrakis ((dimethylthio carbamoyl)oxy) thiacalix[4]arene (CADTTCA), has been investigated for separation and recovery of Pd(II) through solvent extraction technique. Experimental parameters such as contact time, diluents, effect of H⁺ and Cl⁻ concentration, and acid durability have been thoroughly investigated. The loading capacity toward Pd(II) was determined to be 113 mg/L using 0.25 mM CADTTCA. The extractant showed high selectivity and extractability for Pd(II) than the other metal ions present in automotive catalyst residue (ACR) solution containing platinum group (PGMs) metal ions (i.e., Pd(II), Pt(IV), Rh(II), La(III), Al(III) and Ce(III)). The recovery percentage of Pd(II) was 98% after five extraction-scrubbing-stripping cycles. The probable extraction mechanisms were established through the FT-IR spectral analysis.

KEYWORDS:

• Azothiacalix[4]arene derivative
• palladium(II)
• reuse
• solvent extraction

Funding

The research work was financially supported by “Tohoku Innovative Materials Technology Initiatives for Reconstruction (TIMT)” project, “High-Efficiency Rare Elements Extraction Technology Area” under the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan.

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Additional information

Funding

The research work was financially supported by “Tohoku Innovative Materials Technology Initiatives for Reconstruction (TIMT)” project, “High-Efficiency Rare Elements Extraction Technology Area” under the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan.